this.WindowState=FormWindowState.Maximized

------解决方案--------------------
C# code

this.WindowState = FormWindowState.Maximized; //最大化
            this.WindowState = FormWindowState.Minimized; //最小化
            this.WindowState = FormWindowState.Normal;//正常

------解决方案--------------------
探讨

C# code
this.WindowState = FormWindowState.Maximized; //最大化
            this.WindowState = FormWindowState.Minimized; //最小化
            this.WindowState = FormWindowState.Normal;//正常


------解决方案--------------------
 private const int SW_HIDE = 0;
       private const int SW_SHOWNORMAL = 1;
       private const int SW_SHOWMINIMIZED = 2;
       private const int SW_SHOWMAXIMIZED = 3;
       private const int SW_SHOWNOACTIVATE = 4;
       private const int SW_RESTORE = 9;
       private const int SW_SHOWDEFAULT = 10;  

       [DllImport("user32.dll")]
       private static extern bool ShowWindowAsync(IntPtr hWnd, int nCmdShow);  

       private void button1_Click(object sender, EventArgs e)
       {//最小化显示窗体
           ShowWindowAsync(this.Handle, SW_SHOWMINIMIZED);
       }
       private void button2_Click(object sender, EventArgs e)
       {//最大化显示窗体
           ShowWindowAsync(this.Handle, SW_SHOWMAXIMIZED);
       }
       private void button3_Click(object sender, EventArgs e)
       {//还原显示窗体
           ShowWindowAsync(this.Handle, SW_RESTORE);
       }